Fenton Reaction-Generated Advanced Oxidation Protein Products Induces Inflammation in Human Embryonic Kidney Cells.

Fenton reaction is a new mechanism able to generate advanced oxidation protein products (AOPPs) by exposing the human serum albumin to the Fenton system. Here, we characterized the effects of Fenton reaction-generated advanced oxidation protein products (AOPP-FR) on the gene transcription of the nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), and interleukin-6 (IL-6) in human embryonic kidney cells (HEK 293). To investigate the effects of AOPP-FR and AOPP-HOCl on transcription of inflammatory genes, the NF-κB, COX-2, and IL-6 luciferase promoter activities were analyzed. AOPP-FR and AOPP-HOCl were able to induce the activation of the gene transcription of NF-κB, COX-2, and IL-6 in HEK 293 cells. However, the effects of AOPP-FR were significantly higher than the effects of AOPP-HOCl in relation to COX-2 and IL-6. AOPP-FR induces the activation of the gene transcription of NF-κB, COX-2, and IL-6 and may represent a novel pathogenic mediator of inflammation in kidney.

Circulating Double-Stranded DNA in Plasma of Hemodialysis Patients and its Association with Iron Stores.

BACKGROUND: Chronic kidney disease (CKD) is characterized by oxidative stress, and most of the adverse effects of CKD are mediated by iron-catalyzed ROS generation. The DNA, in particular, is more susceptible to attack by ROS than other proteins and membrane lipids. Considering the evidence on the relationship between CKD, iron metabolism, and DNA damage, the purpose of this study was to evaluate cell-free DNA in the plasma of HD patients and its association with iron status biomarkers and kidney function. METHODS: Measurements of the circulating cell-free DNA in plasma, iron, ferritin, transferrin and other biochemical parameters were performed in 40 chronic hemodialysis (HD) patients and 40 healthy controls. Blood samples were also collected 1 hour before and 1 hour after the HD session to check whether a single HD session would be able to promote an increase in cell-free DNA in the plasma. RESULTS: Cell-free DNA in plasma was significantly increased in HD patients in comparison with healthy controls (p = 0.0017), and significant correlations were observed between cell-free DNA and GFR and ferritin. Our findings showed that a single HD session was not able to promote an increase in cell-free DNA. It was reported that increased ferritin levels and reduced GFR were associated with higher circulating cell-free DNA. CONCLUSIONS: The HD patients presented increased ceIl-free DNA. In addition, the increase of ferritin levels and the decrease of GFR were associated with DNA damage. We also observed that a single HD session was not able to promote an increase in cell-free DNA.

An alternative pathway through the Fenton reaction for the formation of advanced oxidation protein products, a new class of inflammatory mediators.

The accumulation of advanced oxidation protein products (AOPPs) has been linked to several pathological conditions, and their levels are formed during oxidative stress as a result of reactions between plasma proteins and chlorinated oxidants produced by myeloperoxidase (MPO). However, it was suggested that the generation of this mediator of inflammation may also occur via an MPO-independent pathway. The aim of this study was to induce the formation of AOPPs in vitro through Fenton reaction and to investigate whether this generation could be counteracted by N-acetylcysteine (NAC) and fructose-1,6-bisphosphate (FBP). The complete Fenton system increased the AOPPs levels and both NAC and FBP were capable of inhibiting the formation of Fenton reaction-induced AOPPs. These data provide a new hypothesis about another pathway of AOPPs formation, as well as report that NAC and FBP may be good candidates to neutralize pro-inflammatory and pro-oxidant effects of AOPPs in several diseases.

Fructose-1,6-bisphosphate and N-acetylcysteine attenuate the formation of advanced oxidation protein products, a new class of inflammatory mediators, in vitro.

The accumulation of advanced oxidation protein products (AOPP) has been linked to several pathological conditions. Previous studies have identified AOPP as a novel biomarker of oxidative damage to proteins and a novel class of mediator of inflammation. The aim of this study was to determine the effects of fructose-1,6-bisphosphate (FBP) and N-acetylcysteine (NAC) as well as the synergistic effect of both treatments on the formation of AOPP in vitro. For this purpose, we incubated the human serum albumin (HSA) with various hypochlorous acid (HOCl) concentrations to produce albumin-advanced oxidation protein products (HSA-AOPP). Both FBP and NAC were capable of inhibiting the formation of HOCl-induced AOPP in a concentration-dependent manner. The synergistic effect promoted by the association of these drugs showed to be more effective than when tested alone. Thus, both FBP and NAC may be good candidates to mitigate and neutralize pro-inflammatory and pro-oxidant effects of AOPP in several diseases.